Another nRF5 based wall switch



  • I'm currently looking into possible solutions for wall switches with high WAF;)
    According to my wife, I'm already quite close, so I want to share my current project status with you and thank all contributors to MySensors.
    My wall switch is mechanically based on http://haus-bus.de The multi push button switches integrate nicely with the Busch Jäger Reflex SI switches, I already have at home.
    I created my own electronics based on the nRF52832 module from Ebyte.
    0_1526025860859_P1030879.JPG
    0_1526025904113_P1030883.JPG
    Besides the Ebyte module, I only have inductors for DCDC mode, a CR2032 battery and the switches on the PCB. The switch cover is semi transparent, so LEDs might be added to give some visual feedback.
    With the CR2032 battery the PCB is quite shallow, so I was able to extend an extisting conventional wall switch by using a double frame.
    0_1526026284166_P1030892.JPG
    0_1526026320853_P1030894.JPG
    0_1526026367887_P1030895.JPG
    0_1526027211696_Zusammenschnitt.jpg
    My measurements show a sleep current of 12 uA, so the battery should be good for about one year. However the nRF52832 should be capable of much less sleep, so I still need to work on that issue.
    If anybody is interested in some more details, I'm happy to share the information.

    Axel


  • Mod

    If the wife says "OK" that is 90% of project success already 😄

    The same principle could be used for a remote control by shrinking the PCB, right?


  • Hardware Contributor

    Nice little project !
    What "connector" do you use to program it on J1 ?

    Is your range not too bad with all the metal (vias, battery, ...) around it ?
    Also, even if in DCDC mode it's not drawing too much current, it's a good practice with button cell to add a capacitor (I suppose 50-100uF is enough with DCDC mode) to "help" the battery during peak current consumption, as it has a high internal resistance and can't supply much current without seeing it's voltage drop.


  • Mod

    maybe a ceramic cap, as the electrolitic ones usually leak some current



  • @nca78
    J1 is http://www.tag-connect.com
    Range is ok for my setup (wall switch and gateway are not too far away from each other), but this is one of the things I want to improve. I will also consider an additional capacitor to decrease the internal resistance of the voltage source. Do you know, if there is anything inside the Ebyte module? I couldn't find any information/schematic. However I need to understand the sleep current and the drawbacks on the battery choice before I build an improved version.

    @gohan
    You are so right and this is my #1 goal with this proof-of-concept. Unfortunately I'm not there yet... Regarding remote control you mean the machnical actuation of the switches? Yes, why not.


  • Hero Member

    @abarkow , did you print the cover? Is it a flat cover or they are cuts between each key?



  • @rvendrame I didn't make the cover on my own, but bought it from haus-bus.de. It's made from acrylic glass with tiny cuts between the keys.


  • Mod

    @abarkow I am talking about an handheld device like a TV remote



  • @abarkow I like european wall switches much more than the US style ones. There is much more room for electronics in them.


  • Hardware Contributor

    @dbemowsk said in Another nRF5 based wall switch:

    @abarkow I like european wall switches much more than the US style ones. There is much more room for electronics in them.

    I agree, I have US/AU here (only a few mm difference) and I wish I had those big 82*82mm squares...


 

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